This application claims priority under 35 U.S.C. 119(a) to Chinese application, serial number 00105255.1 filed Apr. 23, 2000, entitled xe2x80x9cA KIND OF NUMERAL WHEEL COUNTER WHICH CAN OUTPUT SWITCH SIGNALS AND A METHOD OF READING THE SWITCH SIGNALSxe2x80x9d, currently pending.
The present invention relates generally to a measuring instrument and its reading method, and more particularly to a kind of mechanical numeral wheel counter that can output switch signals and the method of reading the switch signals.
Mechanical numeral wheel counters are typically used as measuring instruments. Some applications include kilowatt-hour meters, kilowatt-gas meters, odometers and other types of add-up measuring instruments. Because of its simplicity, stability and reliability in operation, mechanical numeral wheel counters have a long history as measuring instruments and offer a measuring method that cannot be substituted.
The development of new measuring and analysis techniques require the readings or measurements taken by the measuring instruments to be transferred remotely and/or processed by a computer. In such cases, the measurements taken by the measuring instrument should be output as an electrical signal, typically in digital format. However existing numeral wheel counters are mechanical measuring instruments, and have difficulty automatically converting the readings into an electrical signal in digital format. A method and apparatus for digitizing the output of a numeral wheel counter instrument is the problem to be solved.
Some prior art methods have attempted to resolve this problem. One method uses a pulse count for measurement. In this method, the number of rotations of the instrument is measured by optics, magnetism or syntony telepathy method. The pulse or pulse serial is digitally processed by a computer in order to total and store a value. However, there are several disadvantages with this method.
First, the measurement result is obtained by re-calculating a reading instead of reading the measurement instrument directly. The result is a two-scale measurement, one being the original mechanical measurement and the other being the added pulse measurement. The output result is thus not the actual result of the mechanical measurement, but the result of the added electrical measurement.
Second, this method is susceptible to interference by various external factors, such as the weather (thunder and or electrical storms), power supply undulation, other frequency currents and so on. This interference may affect the veracity of measurement results. In addition, the measurement errors will be cumulative and may add up extremely erroneous readings.
Thirdly, this method requires the instrument to be initialized. Since the pulse measurement is the measurement of the course, the final measurement results must be processed and stored by computer. This is inconvenient under many circumstances, such as, for example, when there are large quantities of kilowatt-hour meters to be installed.
Another problem with the pulse measurement method is the pulse measurement instrument must be operating during the actual measurement process. This causes at least two significant problems: first, the relevant electrical elements of the measurement instrument must be operated continuously, otherwise, the result of the measurement may inaccurate; second, the elements that make up the instrument, especially the sensors, may have longevity problems, since they are operating continuously.
One objective of the present invention is to provide a mechanical numeral wheel counter, which can output switch signals.
Another objective of the present invention is to provide a method of reading the switch signals output from the mechanical numeral wheel counter.
In accordance with the present invention, there is provided a mechanical numeral wheel counter, comprising one or more coaxial numeral wheels, and one or more switch sensors set alternatively around the one or more numeral wheels. The circumference of the one or more numeral wheels is divided into several equal spaces, each of the equal spaces having a sensing material applied therewith.
The circumference of the one or more numeral wheels is divided into ten equal spaces, which represent the number 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. There are four sensors set around the circumference of each numeral wheel, the sensors being fixed on the outer part of the numeral wheel.
In one embodiment of the invention, the sensing material may be an absorbency material or a reflecting material.
In another embodiment of the invention the sensing material may also be a magnetic material or a magnetic induction material.
In accordance with the present invention, there is a method of reading the switch signals output from the mechanical numeral wheel counter, dividing the circumference of the numeral wheels into several equal spaces, setting the sensors around the circumference of each numeral wheel, and putting the sensing material on the said spaces. The status of each sensor will be different when the numeral wheel is at a different position. The standard digital waves can be obtained from the processed signals from the sensors, and processed by a single chip computer to read and recognize the signals from the numeral wheel.
By way of example, the absorbency material (shown in black color on FIG. 1) is put on the spaces 1, 3, 6, and 7 and the reflecting material (in white color) is put on the spaces 0, 2, 4, 5, 8, and 9. When the sensor passes the reflecting material (the shown as a white space on FIG. 1), the output signal of the sensor will be 1. When the sensor passes the absorbency material (the black space), the output signal of the sensor will be 0. The output signal from the sensor changes with the rotation of the numeral wheel. Accordingly, if the number read directly on the numeral wheel is 0, a standard digital wave from the sensors corresponding to the reading will be obtained. There is a one to one correspondent relationship between the reading on numeral wheel and the output wave from the sensors. This relationship can be shown as below:
As shown in the above table, the status displayed by the sensors is easily processed as an electronic digital signal. The switch signal from the sensors can be processed simply to get the standard digital square wave, which can be recognized by the single chip computer.
There are some advantages in the method mentioned above: the output of the sensors is simple, easy to recognize and anti-jamming; the output of the sensors is processed by a computer to obtain the digital display signal, thus realizing the direct electrical reading of the digits; it is convenient, and has a long life term, without cumulative errors.